import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import java.io.IOException;
import java.io.PrintWriter;

public class SessionServlet extends HttpServlet {
	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		System.out.println("SessionServlet -- service");
		response.setContentType("text/html");
		PrintWriter out = response.getWriter();
		out.println("<html>");
		out.println("<head><title>SessionServlet</title></head>");
		out.println("<body>");
		String value = request.getParameter("value");
		HttpSession session = request.getSession(true);
		out.println("<br>the previous value is "
				+ (String) session.getAttribute("value"));
		out.println("<br>the current value is " + value);
		session.setAttribute("value", value);
		out.println("<br><hr>");
		out.println("<form>");
		out.println("New Value: <input name=value>");
		out.println("<input type=submit>");
		out.println("</form>");
		out.println("</body>");
		out.println("</html>");
	}
}
